Synthetic fibers and method for producing same



Patented Aug. 20, 1940 UNITED STATES SYNTHETIC FIBERS AND METHOD FOR PRODUCING SAME Jean Marie Alibert, Tassin, France, assignor to E. I. du Pont de Nemours a; Company, Wilmington, Del., a corporation of Delaware No Drawing. Application November 10, 1939,

Serial No. 303,779. 1939 8 Claims.

1 operation whereby the yarn filaments will be broken or torn into fibers of a predetermined staple length.

It has furthermore been proposed to treat multifilament yarns, at spaced intervals along the length thereof, with a material which ,will soften or weaken the filaments, and then subject the weakened filaments-to a sufiiciently drastic stretching operation to sever the filaments at the weakened points.

Such previously known processes for the production of staple fibers from artificial filaments, and threads or yarns composed of such staple fibers have been unsatisfactory as a result of the stretching procedure to which the filaments must be subjected. Such stretching of the filaments subjects them to an internal strain resulting, for example, in a very material reduction of the elasticity of the filaments.

In order to overcome this reduction, or destruction, of the elasticity of the filaments due to the stretching operation, it has heretofore been suggested that the staple lengths of fibers so produced be subjected to a shrinking operation 35 whereby to regain the loss of elasticity and elongation brought about by the stretching thereof.

It has now been discovered that the disadvantages of prior known processes can be substantially eliminated by treating multifilament 40 yarns with a material which will substantially disintegrate, or destroy, the filament structure at spaced intervals along their lengths when the treated yarns are subsequently subjected to a treatment with heat so that substantially no tension need be applied to the filaments to break or sever them at the disintegrated sections.

It is, therefore, an object of the present invention to produce staple fibers from artificial filaments, and yarns composed of such staple fibers by applying to continuous artificial filaments, at spaced points along the length thereof, a distin tegrating material for said filaments, and subjecting the said filaments to a heat treatment which is sufiiciently drastic to cause said filaments to be disintegrated by said material.

In France January 13,

Other objects of the invention will appear hereinafter.

In accordance with the present invention one or more yarns composed of continuous artificial filaments are contacted, at spaced points along 5 the length of the yarn, with a material which will disintegrate the structure of said filaments, and then subject the yarns to a sufliciently drastic heat treatment to cause said filaments to be disintegrated by said material applied thereto.

The process of the present inventionmay be applied to regenerated cellulose yarns, yarns composed of cellulose derivatives, such as cellulose esters or cellulose ethers, or to yarns formed from any other composition used in the manufacture of continuous filaments, and which can be distintegrated by the application of a disintegrating material, for example, a composition of polyvinyl alcohol, polyvinyl esters, interpolymers of vinyl chloride and vinyl acetate, and polymer- 20 ized esters of acrylic and alkacrylic acids.

The invention is applicable to the treatment of single yarns of continuous filaments, or to a plurality of yarns which are combined in the form of ropes or bundles. The invention is furthermore applicable to the treatment of yarns-immediately after their extrusion and solidification, or to yarns which have previously been collected or wound in suitable package form.

When applied to individual yarns the disintegrating material may be applied intermittently by means of a revolving brush or by causing the filaments to have intermittent contact with a wick containing the disintegrated material or by causing the yarns to have intermittent contact with a roll rotating in a bath of the disintegrating material. The individual yarns thus treated may, if desired, be dried and wound in the form of a cake or skein, or they may be otherwise collected. and then subjected to a heat treatment, for example, a baking treatment or a hot steam treatment, whereby to cause said disintegrating material to react with the filament structure to disintegrate the same.

The process of the present invention can be utilized for the production of a sliver of staple length filaments by the following procedure. Several individual yarns of continuous filaments are passed into intermittent contact with an element containing a solution of a disintegrating material. The individual yarns are then brought together to form a bundle or rope which,after a "drastic heat treatment to cause the disintegration of the filaments to take place at the points where 4 they have been contacted, can be subjected tofa preliminary drawing operation to sever the filaments into staple lengths. Thereafter the sliver thus formed may be drawn and twisted in a conventional manner to form a spun yarn. In this procedure it is preferred that the individual yarns of which the rope is composed will contain the disintegrating material at points along the lengths of the several yarns in staggered relationship to each other so that the subsequently formed staple fibers will overlap each other. Furthermore, if it is undesirable to bring the individual yarns into contact with each other to form the rope while the yarns are still wet with the disintegrating fluid, the individual yarns may be passed over a drying roll to dry the disintegrating material on the yarn before the individual yarns are brought together to form the rope or bundle. Such a drying of the individual yarns is conducted at a sufiiciently low temperature or for a sufficiently short time to prevent the disintegrating action from taking place at this stage of the production.

As disintegrating materials the following have been found to produce particularly desirable results in accordance with the present invention: When the material of which the yarn is composed is regenerated cellulose, any product normally used for carbonizing of the cellulose materials may be used, for example, solutions of sulfuric acid, hydrochloric acid, salts of these acids which will decompose at an elevated temperature such as aluminum chloride, magnesium chloride and the like.

When the filaments are composed of a cellulose ester, a cellulose ether, a derivative of polyvinyl acid, an interpolyrner of vinyl chloride and vinyl acetate, a polymerized ester of acrylic or alkacrylic acid, benzoyl peroxide or a mixture of materials capable of forming benzoyl peroxide, as described in French Patents Nos. 788,592 and 837,331, may be employed.

If the filaments to be treated are composed of a mixture of regenerated cellulose filaments and organic derivatives of cellulose or polyvinyl derivatives, magnesium perchlorate can, for example, be used. Obviously, many other substances which are known to disintegrate the particular filaments used in the process can be employed.

The disintegrating materials can be deposited on the filaments by any suitable applicating means which is capable of applying a disintegrating material at spaced points along the length of the yarns or filaments. For example, either a wick dipping into a liquid disintegratingmaterial or a roll revolving in such a liquid may be used, the filaments being brought into contact with the wick or the roll from time to time by suitable mechanical device. The disintegrating material may be in the form of a liquid or paste or the disintegrating material may be applied in the gaseous state by periodically directing the gas against the filaments or yarns.

In order to more clearly illustrate the principles of the invention the following detailed examples are submitted, it being understood that the invention is not to be limited to the specific details set forth therein.

Example I temperature of 70 C. for a sufficient period of time to dry the same, and they are then combined into a rope with an assembling twist of 15 turns per meter. The rope so obtained is subjected to a heat treatment at 110 C. for 20 minutes in an oven with air circulation. The resulting rope or bundle is composed of filaments which are substantially completely disintegrated at spaced points along their lengths. The rope is then passed through a drawing frame of the type employed for spinning natural fibers. The passage of the sliver through the drawing frame will cause the filaments to be parted to form a sliver of uniform length staple fibers without the application of any substantial tension on the filaments. A spun yarn composed of staple fibers is then formed by a conventional drawing and twisting operation.

Example II A cellulose acetate yarn as it emerges from a cellulose acetate spinning cell is brought into periodic contact with a metal roll revolving in a trough containing a substantially saturated solution of benzoyl peroxide in benzine. The yarn is then wound .on a bobbin, and the package subjected to steaming for 35 minutes at a temperature of 110 C. to 115 C. The yarn so produced is plied with one or more like yarns and is drawn and spun to form a spun staple fiber yarn in the customary manner.

Example III A mixed yarn comprising continuous filaments of cellulose acetate and regenerated cellulose is passed into intermittent contact with a roll revolving in a trough, containing the following solution:

' Grams Aluminum perchlorate 3 Gum arable 0.5

' Glycerol 1 Water 95.5

The yarn is passed into contact with an air current having a temperature of 70 C. for a sufficient period of time to evaporate a major part of the water serving as a carrier for the perchlorate. A plurality of the mixed yarns is plied with a twist of 10 turns per meter to form a rope which is subjected to a heat treatment for a period of 30 minutes at 110 C. to cause disintegration of the filaments at the points along the length thereof containing the perchlorate. The rope so obtained can be directly drawn and twisted as in Examples I and II to form a spun staple fiber yarn in which the staple fibers have the same physical characteristics as the untreated continuous filaments.

It is of the essence of the present invention to treat the filaments and yarns with a disintegrating material which will cause the filamentsto be sufficiently disintegrated at spaced points along the length thereof that a pull of insuificient tension to subject the filaments to an internal strain will rupture the same at the said points. The staple fibers contained in the spun yarns produced in accordance with the present invention will have substantially the same elasticity and elongation as the original continuous filaments from which they are produced. Furthermore, the ruptured ends of the filaments will be substantially smooth and of the same crosssection as the other sections of the filaments.

Since it is obvious that many changes and modifications can be made in the details as above described, it is to be understood that the invention is not to be limited to these details earcept as set forth in the appended claims. I Y

I claim: I

1. In v the production of staple fibers" from artificial filaments and threads composed of such staple fibers, the steps comprising applyingto,v

continuous artificial filaments, at spaced intervals along the length thereof, a disintegrating material for said filaments, and subjecting said filaments to a heat treatment which is sufiicient- 1y drastic that a pull on said filaments of insufficient tension to subject them to internal strain will rupture the same.

2. In the production of staple fibers from artificial filaments and threads composed of such staple fibers, the steps comprising applying to continuous artificial filaments, at spaced intervals along the length thereof, a liquid disintegrating material for said filaments, and subjecting said filaments to a heat treatment which is sufilciently drastic that a pull on said filaments of insufficient tension to subject them to internal strain will rupture the same.

3.'In'the production of threads composed oi staple fibers from artificial filaments, the steps comprising applying to a plurality of yarns of continuous artificial filaments,'atspaced intervals along the length thereof, a liquid disintegrating material for said filaments, combining said yarns to form a rope, and subjecting said' rope to a heat treatment which is suificiently drastic that a pull on said filaments of insufiicient tension to subject them to internal strain will rupture the same.

4. In the production of threads composed of staple fibers from artificial filaments, the steps comprising applying to a plurality ofyarns of continuous artificial filaments, at spaced inter"- vals along the length thereof, a liquid disintegrating. material for said filaments, combining 'said'yarns to form a rope, subjecting said rope ,'to a heat treatment which is sufliciently drastic that a pull on said filaments of insufiicient tension to subject them to internal strain will rupture the same to form a sliver, and drawing and twisting said sliver to form a spun yarn.

5.;In the production of threads composed of staple fibers from artificial filaments, the steps comprising applying to a plurality of yarns of continuous artificial filaments, at spaced inter- "vals along the length thereof, a liquid disintesaid sliver to form a spun yarn.

6. 'Ifhe process of claim 1 in which the arti- "ficial filaments are composed of regenerated cellulose.

'7. The process of claim '1 in which the artificial filaments are composed of an organic cellulose derivative.

8. The process of claim 1 in which the aridficial filaments are composed of a polyvinyl acid derivative.

JEAN MARIE ALIBERT. 

